April 11, 2017—KB4015221 (OS Build 10240.17354)

Improvements and fixes

This update includes quality improvements. No new operating system features are being introduced in this update. Key changes include:

Addressed issue where the copy operation fails when copying a file that has Encrypted File System (EFS) encryption to a share that is not encrypted by EFS.

Addressed an issue where CredentialGuard-enabled computers joined to Active Directory domains submit two bad logon attempts each time a bad password is provided during a Kerberos-based logon. Logons to Active Directory domains with arbitrarily low account lockout thresholds may be subject to unexpected account lockouts. For example, 2 logons with a bad password could result in an account being locked out if the account lockout threshold is set to 3 or 4.

Addressed issue that prevents the launch of the Delete Browsing History window in Internet Explorer.

File informationFor a list of the files that are provided in this update, download the file information for cumulative update 4015221. If you're installing a Windows 10 update for the first time, the package size for the X86 version is 505 MB and the package size for the x64 version is 1,104 MB.